Wall Street analysts say the company's drug could still reach the market but with restrictions or a requirement for a large, follow-up safety study. That could be a major financial hurdle for the small, North Carolina company, according to analysts.

Cempra is among a handful of drugmakers working on new antibitiocs as many bacterial strains have grown resistant to decades-old drugs like penicillin.

The Food and Drug Administration posted its review of the drug online Wednesday, ahead of a public meeting where outside experts will assess the medication. FDA staffers said Cempra's drug worked as well as an older drug for treating a form of pneumonia.